Get absolute performance with Steeda's 8mm, spiral-core, silicone, plug wires or Motorsport 9mm ignition wire. Spiral-core, silicone, plug wires out perform the other leading wires. From Neoprene to Hypalon to Silicone, dielectric strength was increased with each new material. Our 8mm spiral-core, silicones are better than most 10+mm wires. Tailored for a perfect fit, these are the ultimate plug wires for your high performance Mustang.